Fujitsu AOTG30KMTC, Service Manual, Page: 55 / 199

2-4. E: 18. External communication error (Indoor unit)
Indicator
Indoor unit
Operation indicator 1 time flash
Timer indicator 8 time flash
Economy indicator Continuous flash
Error code E: 18
outdoor unit
Refer to “Error code table (Outdoor unit: for 34 model
only)” on page 1
Detective actuator Indoor unit
External
communication
error After receiving a signal from the external input and
output PCB, the same signal has not been received for
15 seconds.
Forecast of cause
Connection failure
External input and output PCB failure
Controller PCB
Check point 1. Check the connection
• Check any loose or removed connection betw een the main PCB to the external input and out-
put PCB.
-> If there is an abnormal condition, correct it by refer to the installation manual or the “DESIGN
& TECHNICAL MANUAL”.
• Check the connection condition on the external input and output PCB and the main PCB (If
there is loose connector, open cable or mis-wiring.)
↓
Check point 2. Replace the external input and output PCB
If check point 1 do not improve the symptom, change external input and output PCB
↓
Check point 3. Replace main PCB
If check point 2 do not improve the symptom, change main PCB
↓
End
2-4. E: 18. External communication error (Indoor unit)
- (03-17) -
2. Troubleshooting with error code
TROUBLESHOOTING TROUBLESHOOTING